This invention relates in general to fiber-optic receiver/transmitter arrangements and more specifically to a novel loss of optical input circuit for a fiber-optic receiver.
Fiber-optic receivers and transmitters or fiber-optic interface units are used in modern telecommunications and data transmission systems between an optical fiber transmission line and electronic digital equipment. The fiber-optic transmitter receives electrical signals from the electronic equipment representing the data to be transmitted. The transmitter then converts the data to light pulses which are coupled to an optical fiber transmission line. The fiber-optic receiver receives light pulses representing the transmitted data from an optical fiber transmission line and converts the light pulses to electrical signals which are sent to and processed by the electronic digital equipment. These systems work in very high transmission rates from 145 Mbs to 2400 Mbs (Megabits per second).
Transmission of data or other signals along optical fiber transmission lines have advantage in the fact that light rays are almost immune to electromagnetic interference such as sparks, lightening, crosstalk and other interference which may be induced into the transmission line.
It is advantageous in fiber-optic receivers of the type discussed above to ascertain if a reliable optical input signal is being received. The fiber-optic receiver then can send warning alarms to a system controller notifying that a problem exists on the transmission line.
It therefore becomes an object of the present invention to disclose a novel loss of optical input signal detector which can detect the loss of the optical input signal and signal a system controller of the problem.